Nuclear clefts in chronic lymphocytic leukaemia. A light microscopic and ultrastructural study of a new prognostic parameter

Atypical Chronic Lymphocytic Leukemia-The Current Status

A diagnosis of typical chronic lymphocytic leukemia (CLL) requires the presence of ≥5000 clonal B-lymphocytes/μL, the coexistence of CD19, CD20, CD5, and CD23, the restriction of light chain immunoglobulin, and the lack of expression of antigens CD22 and CD79b. Atypical CLL (aCLL) can be distinguished from typical CLL morphologically and immunophenotypically. Morphologically atypical CLL cells have been defined mainly as large, atypical forms, prolymphocytes, or cleaved cells. However, current aCLL diagnostics rely more on immunophenotypic characteristics rather than atypical morphology. Immunophenotypically, atypical CLL differs from classic CLL in the lack of expression of one or fewer surface antigens, most commonly CD5 and CD23, and the patient does not meet the criteria for a diagnosis of any other B-cell lymphoid malignancy. Morphologically atypical CLL has more aggressive clinical behavior and worse prognosis than classic CLL. Patients with aCLL are more likely to display markers associated with poor prognosis, including trisomy 12, unmutated IGVH, and CD38 expression, compared with classic CLL. However, no standard or commonly accepted criteria exist for differentiating aCLL from classic CLL and the clinical significance of aCLL is still under debate. This review summarizes the current state of knowledge on the morphological, immunophenotypic, and genetic abnormalities of aCLL.

Acute lymphoblast leukemia in sheep induced by inoculation of bovine leukemia virus: diagnostic electron microscopic morphological study

Six control lambs were inoculated with Tris buffer, 7 lambs were inoculated with an early passage of bovine leukemia virus (B.L.V.) culture, and 7 lambs with a late passage B.L.V. All experimental lambs were positive with the agar gel immunodiffusion assay (AGID) within 3 months of inoculation and remained positive throughout the 8-year duration of the experiment. The earliest onset of leukemia was at 14 months and the latest was at 44 months after inoculation. Five lambs died with leukemia, two were inoculated with early passage, and three were inoculated with late passage of B.L.V. Eight years after the inoculation, the remaining nine inoculated lambs were clinically normal. The diagnostic ultrastructural morphology of the leukemic lymphoblasts in this study were characterized by hand-mirror cells, multiple nucleoli, irregular nuclear contour with deep indentions, electron-dense granules in the euchromatin, and nuclear cytoplasmic pockets, nuclear myelin figures, mitochondrial variation in size and density, disruption of rough endoplasmic reticulum, and increased ribosomal density. This study shows abundant cytoplasmic processes of hairy cell leukemia. The nuclei of the leukemia lymphoblasts showed electron-dense granules of varying sizes, which were not seen in any of the normal lymphoblasts.

Aberrant morphology, proliferation, and apoptosis of B-cell chronic lymphocytic leukemia cells

B-cell chronic lymphocytic leukemia (CLL) has been traditionally described as a disease characterized by an accumulation of quiescent small lymphocytes with decreased susceptibility to apoptotic cell death. However, small numbers of "atypical" lymphocytes and prolymphocytes (PL) are frequently observed in the bone marrow (BM) of patients with CLL. In this study, we examined BM biopsy and aspirate specimens obtained from seven patients with atypical CLL. Using a double labeling (Ki-67+/CD20+) immunohistochemical method, we found that an appreciable number of the atypical CLL cells expressed the proliferation-associated protein Ki-67. Because CLL is characterized by a slow change in the peripheral blood (PB) lymphocyte count, we reasoned that a subpopulation of CLL cells probably undergoes spontaneous apoptosis. Using Western blot analysis, we observed expression of procaspase-9, procaspase-10, and poly(ADP-ribose) polymerase by the neoplastic cells in all seven cases of CLL, and procaspase-3 and procaspase-8 expression in six neoplasms. We also detected cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase in four and five CLL cases, respectively. To determine whether CLL cells undergo spontaneous apoptosis, we performed the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay using BM biopsy specimens. We found TUNEL-positive lymphocytes in areas infiltrated by CLL. In summary, our data show that subpopulations of B-lymphocytes are proliferating or undergoing spontaneous apoptotic cell death in patients with atypical CLL.

Albumin enhanced morphometric image analysis in CLL

BACKGROUND

The heterogeneity of lymphocytes from patients with chronic lymphocytic leukemia (CLL) and blood film artifacts make morphologic subclassification of this disease difficult.

METHODS

We reviewed paired blood films prepared from ethylene-diamine-tetraacetic acid (ETDA) samples with and without bovine serum albumin (BSA) from 82 CLL patients. Group 1 adhered to NCCLS specifications for the preparations of EDTA blood films. Group 2 consisted of blood films containing EDTA and a 1:12 dilution of 22% BSA. Eight patients were selected for digital photomicroscopy and statistical analysis. Approximately 100 lymphocytes from each slide were digitally captured.

RESULTS

The mean cell area +/- standard error was 127.8 microm(2) +/- 1.42 for (n = 793) for group 1 versus 100.7 microm(2) +/- 1.39 (n = 831) for group 2. The nuclear area was 88.9 microm(2) +/- 0.85 for group 1 versus 76.4 microm(2) +/- 0.83 for group 2. For the nuclear transmittance, the values were 97.6 +/- 0.85 for group 1 and 104.1 +/- 0.83 for group 2. The nuclear:cytoplasmic ratios were 0.71 +/- 0.003 for group 1 and 0.78 +/- 0.003 for group 2. All differences were statistically significant (P < 0.001).

CONCLUSIONS

BSA addition results in the reduction of atypical lymphocytes and a decrease in smudge cells. BSA also decreases the lymphocyte area and nuclear area, whereas nuclear transmittance and nuclear:cytoplasmic ratio are increased. A standardized method of slide preparation would allow accurate interlaboratory comparison. The use of BSA may permit better implementation of the blood film-based subclassification of CLL and lead to a better correlation of morphology with cytogenetics and immunophenotyping. Published 2003 Wiley-Liss, Inc.

Lymph node histology in typical and atypical chronic lymphocytic leukemia

According to the French-American-British (FAB) proposal on the classification of chronic lymphoid leukemia (CLL), the disorder can be subdivided into typical and atypical CLL. We recently demonstrated the prognostic significance of this subgrouping and based on these results we suggested that typical and atypical CLL represent two closely related, but different entities. These results prompted us to investigate 42 patients diagnosed with CLL based on the results of lymph node biopsy in order to identify the histologic counterpart of the CLL variants. A first group of 14 cases showed a monomorphic proliferation of small round lymphocytes associated with the occurrence of small pseudofollicles. All these cases were diagnosed as typical CLL on peripheral blood (13 cases) or bone marrow smear (1 case). The remaining 28 cases showed aberrant histologic features characterized by the presence of large numbers of paraimmunoblasts and prolymphocytes, forming very large pseudofollicles, and/or by nuclear irregularities of the neoplastic cells. Based on peripheral blood smears (22 cases) or bone marrow smears (six cases), two cases showed no peripheral blood involvement, 21 cases were diagnosed as atypical CLL, and five as typical CLL. From these data we can conclude that a histologic counterpart of the CLL variants recognized in the FAB proposal does exist; moreover, our data may explain reports on lymph node involvement by CLL composed of small cleaved cells and clarify the occurrence of pseudofollicles in cases described as mantle cell lymphomas.

Chronic lymphocytic leukaemia: prognostic value of lymphocyte morphological subtypes. A multivariate survival analysis in 146 patients

Among other patient and disease characteristics, different morphological lymphocyte subtypes were analysed in 146 patients with chronic lymphocytic leukaemia (CLL) to establish their clinical significance and prognostic value. The univariate analysis selected, among other well-known variables, the following lymphocyte subtypes as significant in prognosis: prolymphocytes, granulated lymphocytes, cleaved lymphocytes and small-size lymphocytes. The presence of prolymphocytes and cleaved lymphocytes was correlated with a poor prognosis, whereas granular lymphocytes and small-size lymphocytes were related to a good prognosis. A multivariate regression analysis showed that, besides clinical stages, haemoglobin level, WBC count, age, percentage of bone marrow erythroid cells, and sex, only prolymphocytes had independent prognostic significance. Prolymphocyte percentage correlated positively with characteristics expressing tumour mass such as WBC count, blood absolute lymphocyte count, serum lactate dehydrogenase level, number of enlarged lymph nodes, splenomegaly, and a high number of lymphocytes in bone marrow aspirate. Finally, a prolymphocyte threshold of 5 x 10(9)/l was found to be useful not only to separate two different groups of patients in the whole series but also in Rai's stages II and III + IV, and in Binet's stages A and C.

Investigation of nuclear clefts as a prognostic parameter in chronic lymphocytic leukemia

The importance of cell morphology with respect to the presence or absence of nuclear clefts (NC) in peripheral blood lymphocytes has been investigated in 86 previously untreated chronic lymphocytic leukemia (CLL) patients. Cleaved cells were considered to be present in significant numbers when they exceeded 5% of the peripheral blood lymphocytes. On this basis patients could be divided into two morphological groups. Age, sex and distribution of stages, as well as mode of clinical presentation were alike in the two groups of patients. In contrast, lymph node involvement was more frequently encountered in patients with NC greater than 5% (p less than 0.01). Both survival and treatment-free period probabilities were not statistically correlated to the quantitative changes in the percent value of NC. We further confirm that Binet's clinical staging is a significant predictor of survival irrespective of NC.

Investigation of cell size and nuclear clefts as prognostic parameters in chronic lymphocytic leukemia

The importance of the size and morphology of peripheral blood lymphocytes has been controversial as prognostic indicators in chronic lymphocytic leukemia (CLL). This study was initiated to specifically examine cell size and morphology with respect to presence or absence of nuclear clefts and the relative importance to survival. Eighty-seven cases of CLL that had not been previously treated were examined. Cleaved cells were considered present in significant numbers when they exceeded 5% of the circulating lymphocytes. Prognosis was not statistically significant when cell size and nuclear clefts were examined individually and in combination. This study confirms that clinical staging is the significant prognostic predictor irrespective of cell size and/or nuclear configuration.

Lymphoproliferations in the bone marrow: identification and evolution, classification and staging

Bone marrow biopsies from 3229 patients with lymphoproliferative disorders and 1156 patients with benign or reactive lymphoproliferations were investigated and criteria for distinguishing between them are given. Bone marrow involvement was found in 89% of multiple myeloma, 64% of non-Hodgkin's lymphomas and 8% of Hodgkin's disease. According to the predominant proliferative cell type there were five major entities in multiple myeloma and non-Hodgkin's lymphomas: (1) plasmacytic; (2) lymphocytic; (3) hairy cell; (4) immunocytic; (5) centrocytic. These were further classified into distinct subtypes each of which had independent prognostic significance. The mode of spread of the lymphoproliferative disorders in the bone marrow showed one of six architectural patterns, which together with the quantity of infiltration in the biopsy (reflecting the tumour cell burden) had significant predictive value. These results demonstrate the value of bone marrow biopsies in the identification, classification and staging of lymphoproliferative disorders, as well as in monitoring the course of disease and the response to therapy.

Therapeutic cytapheresis in chronic lymphocytic leukemia

The role of therapeutic reductive lymphapheresis in 59 patients with chronic lymphocytic leukemia (CLL) was reviewed. Reduction in lymphocytosis, lymphadenopathy and hepatosplenomegaly was noted in 50%-60% of the patients studied. In addition to mobilization of the lymphoid tumor load, 40% of the patients showed an improvement in their hemogram. Although apheresis-induced anemia can occur, reported complications were minimal. These studies suggest that a majority of CLL patients might benefit from therapeutic lymphapheresis.